📚 Question Bank

Tere major is not involved in a patient with rotator cuff tear.

The rotator cuff is a group of 4 muscles (SITS) that stabilizes the shoulder joint:

The muscle marked in the image is the teres major and it is supplied by the lower subscapular nerve.

In the above scenario, innervation to latissimus dorsi is most likely to be damaged.

Latissimus dorsi is innervated by the thoracodorsal nerve, which could be injured during radical mastectomy. It has the following actions on the arm:

• Extension
• Adduction
• Medial rotation

Muscles Supraspinatus

Deltoid

Infraspinatus Teres minor Teres major

Latissimus Dorsi

The long head of the triceps Pectoralis major

Actions

Steadies the head of the hum erus during movements, abd uction of shoulder joint from 0-15°

Abduction, anterior fibers - fl exors and medial rotators, po sterior fibers - extensors and lateral rotators

Lateral rotator of the arm Lateral rotator of the arm

Adduction and medial rotatio n of the arm

Adduction, medial rotation, a nd extension of the arm

Extension of elbow joint

Adduction, medial rotation, a nd flexion of the arm

The above image shows the Popeye sign, which is seen in the proximal biceps tendon rupture.

Popeye sign is seen on flexing the elbow. An extremely prominent bulge of the muscle belly occurs as its unrestrained fibers contract.

The proximal biceps tendon makes up 90-97 of all biceps tendon ruptures. In isolation, it has little effect on the upper limb function but produces a characteristic deformity called the Popeye sign.

Note:

The 4 most common areas of tendon rupture include quadriceps, achilles, rotator cuff (most commonly supraspinatus), and biceps.

The long head of triceps and biceps brachii cross both shoulder and elbow joints, hence acting on both joints.

Muscles

Anterior compartm ent

Coracobrachialis Brachialis Biceps Brachii

Posterior compart ment

Triceps brachii

Origin

Coracoid Process of scapul a

Distal half of anterior aspec t of humerus

Short head: Coracoid proce ssLong head: Supraglenoid tubercle

Long head: Infraglenoid tu bercleMedial and Lateral h eads: Posterior surface of H umerus

Insertion

The medial side of midshaf t of humerus

Ulnar tuberosity Radial tuberosity

Olecranon process of ulna

Innervation

Musculocutaneous nerve

Musculocutaneous and radi al nerve

Musculocutaneous nerve

Radial nerve

The nerve shown in the image is the musculocutaneous nerve. It penetrates and innervates the coracobrachialis.

In the axilla, the medial surface of the coracobrachialis is pierced by the musculocutaneous nerve, which innervates it and then passes through the muscle to enter the arm. Then innervates all the muscles of the anterior compartment of the arm (i.e. biceps brachii, and brachialis)

The image above shows the radius, identified by the radial head at the elbow joint. The arrow points to a raised area, which is the radial tuberosity. Biceps brachii is attached to the radial tuberosity.

The short head of the biceps brachii originates from the apex of the coracoid process and the long head arises from the supraglenoid tubercle of the scapula. Both the tendons end in a flattened tendon and are attached to the radial tuberosity. The nerve supply is by the musculocutaneous nerve (C5, C6).

Flexor digitorum superficialis (FDS) is not a composite muscle.

A composite muscle is innervated by more than 1 nerve. Since FDS is supplied by the median nerve (C8, T1) only, it is not a composite muscle.

Muscle Subscapularis

P. Major Trapezius Brachialis

Flexor digitorum profund us

Flexor pollicis brevis

Innervation

Upper and lower subscapular nerves

Medial and lateral pectoral n erves

Motor: Spinal accessory nerv eProprioception: C3, C4

Motor: Musculocutaneous ne rveProprioception: Radial ne rve

Medial half ulnar nerveLater al half anterior interosseous nerve

Superficial head: Median ner veDeep head: Deep branch of ulnar nerve

Extensor carpi radialis longus (ECRL) and brachioradialis are supplied by the radial nerve (C6 and C7) before its division into superficial and deep branches in the lateral wall of the cubital fossa.

The deep branch of the radial nerve after penetrating the supinator is called the posterior interosseous nerve, which innervates all extrinsic wrist extensors except ECRL.

Muscles in the anterior compartment of the forearm:

Muscles Superficial layer

Flexor carpi ulnaris (FCU)

Palmaris longusFlexor carpi r adialis (FCR)Pronator teres

Intermediate layer

Flexor digitorum superficialis Deep layer

Flexor digitorum profundus (

FDP)

Flexor pollicis longus (FPL)P ronator quadratus

Innervation

Ulnar nerve Median nerve

Median nerve

Lateral half: Anterior interos seous nerveMedial half: Ulna r nerve

Anterior interosseous nerve

Muscles of the posterior compartment of the forearm

Muscles Superficial

BrachioradialisExtensor carpi radialis longus (ECRL)

Extensor carpi radialis brevis

(ECRB)

Extensor digitorumExtensor digiti minimiExtensor carpi u lnaris

Anconeus Deep

SupinatorAbductor pollicis lo ngus (APL)Extensor pollicis b revis (EPB)Extensor pollicis l ongus (EPL)Extensor indicis

Innervation

Radial nerve before division

Radial nerve deep branch bef ore penetrating supinator

Posterior interosseous nerve

Radial nerve

Posterior interosseous nerve

Flexor pollicis longus (FPL) is most likely to be affected in a patient with acute compartment syndrome of the anterior forearm as it is present in the deep layer.

Muscles in the anterior compartment of the forearm:

Muscles Superficial layer

Flexor carpi ulnaris (FCU)

Palmaris longusFlexor carpi r adialis (FCR)Pronator teres

Intermediate layer

Flexor digitorum superficialis Deep layer

Flexor digitorum profundus (

FDP)

Flexor pollicis longus (FPL)P ronator quadratus

Innervation

Ulnar nerve Median nerve

Median nerve

Lateral half: Anterior interos seous nerveMedial half: Ulna r nerve

Anterior interosseous nerve

Palmar interossei is a unipennate muscle.

A muscle with a central tendon towards which the fibers converge on either side is called the bipennate muscle.

• Bipennate -
• Medial 2 lumbricals
• Dorsal interossei
• Unipennate -
• Lateral 2 lumbricals
• Palmar interossei

Overview of Muscles of the hand:

Intrinsic muscles

Adductor PollicisPalmaris Br evisInterosseiLumbricalsthen arHypothenar

Precision grip to execute prec ision movements

Extrinsic muscles

Originate in the forearm, ins ert in the hand

Power grip for forceful grip w ith hand

The test being performed in the above-shown image is the card test for the palmar interossei muscle. The 3rd metacarpal (middle finger) has no palmar interosseous attachment.

Palmar interossei lie on the palmar surface of the metacarpals. There are 3 palmar interossei:

• 2nd metacarpal (Ulnar side)
• 4th metacarpal (Radial side)
• 5th metacarpal (Radial side)

Note: There may be 4 interossei in some people.

The muscle marked 'A' is lumbricals and they cause flexion at the metacarpophalangeal joints.

Lumbricals are intrinsic muscles of the hand that flex the metacarpophalangeal joints (MCP) and extend the interphalangeal joints (PIP amp; DIP).

They originate from flexor digitorum profundus.

• The lateral two are unipennate, supplied by the median nerve.
• The medial two are bipinnate, supplied by the ulnar nerve.

Power grip is by extrinsic muscles of the hand (long flexors).

Extrinsic muscles of the hand originate in the forearm and insert in the hand i.e. long flexors. Precision grip is a function of the intrinsic muscles of the hand.

Intrinsic muscles of the hand originate and insert in the hand.

• Adductor pollicis
• Palmaris brevis
• Interossei, lumbricals
• Thenar, hypothenar

The costocervical trunk is not a branch of the 1st part of the subclavian artery. It is a branch of the 2nd part.

Scalenus anterior divides the subclavian artery into 3 parts:

1stpa rt

2ndp art

3rdp art

Branches

Vertebral artery(Largest bran ch)Internal thoracic arterySu perior epigastric arteryMuscu lophrenic arteryThyrocervical trunkSuprascapular arteryIn ferior thyroid arteryTransver se cervical artery

Costocervical trunk Dorsal scapular artery

The axillary artery is divided into 3 parts by the pectoralis minor muscle.

The axillary artery is the continuation of the subclavian artery. It extends from the outer border of the 1st rib to the lower border of teres major.

Pectoralis minor divides the artery into 3 parts:

After passing the lower margin of the teres major, it becomes the brachial artery.

Part

1st pa rt

2nd p art

3rd p art

Relation to Pectoralis minor Lies proximally

Lies posteriorly Lies laterally

Branches

Superior thoracic artery Thoracoacromial trunk

Subscapular arteryAnterior ci rcumflex humeral arteryPost erior circumflex humeral arte ry

Anastomosis around the scapula maintains circulation to the upper limb if the blood supply is interrupted (fractures or dislocation of the shoulder joint). Anastomosis occurs between the 1st part of the subclavian artery and the 3rd part of the axillary artery. These arteries also anastomose with intercostal arteries.

The axial artery of the upper limb is the subclavian artery. Anastomosis around the scapula:

Level of anastomosis Body of Scapula

Deep branch of transverse ce rvical artery

Circumflex scapular artery Inferior angle of scapula

Subscapular artery Acromion process

Suprascapular artery (Acromi al branch)

Posterior circumflex humeral artery (Acromial branch)

Arteries involved Suprascapular artery Thyrocervical trunk

Subscapular artery

Deep branch of transverse ce rvical artery

3rd part axillary artery

Thoraco-acromial artery (Acr omial branch)

Thyrocervical trunk 3rd part axillary artery

Branch of Thyrocervical trunk

Thyrocervical trunk

2nd part axillary artery

The branches of the third part of the axillary artery supply the surgical neck of the humerus. Thrombus in this part will cause decreased supply in its branches - the anterior and posterior circumflex humeral arteries.

Branches of 3rd part of the axillary artery are:

• Anterior circumflex humeral arteries
• Posterior circumflex humeral arteries
• Subscapular artery (not involved in the anastomosis)

Fracture of the surgical neck is the commonest site among all proximal humerus fractures due to its inherent weakness. Fracture at this site may cause injury to the posterior circumflex humeral

artery and the axillary nerve that accompanies it.

Positional compression of the axillary artery is seen in athletes who are involved with throwing movement, as in baseball players. Repeated movement of the humerus may cause compression of the distal part of the axillary artery. This may lead to thrombosis or aneurysm resulting in arm ischemia.

The anterior circumflex humeral artery is a branch of the axillary artery. Hence, it is unlikely to have a decreased flow due to blockage in the brachial artery.

The brachial artery has 3 branches:

• Profunda brachii (accompanies radial nerve in the spiral groove) gives off nutrient artery to the humerus and an ascending branch which anastomoses with posterior circumflex humeral artery.
• It then divides into:
• Anterior descending artery (Radial collateral artery)
• Posterior descending artery (Middle collateral artery)
• Superior ulnar collateral artery (accompanies ulnar nerve)
• Inferior ulnar collateral (supratrochlear) artery

The image given below shows branches of the brachial artery.

The interosseous recurrent artery is a branch of the posterior interosseous artery.

The posterior interosseous artery originates from the common interosseous branch of the ulnar artery. It contributes a branch, the recurrent interosseous artery to the vascular network around the elbow joint.

The anterior interosseous artery passes through the opening in the interosseous membrane.

The anterior interosseous artery passes distally along the anterior aspect of the interosseous membrane and supplies muscles of the deep compartment of the forearm, radius, and ulna.

Perforating the interosseous membrane in the distal forearm, the anterior interosseous artery terminates by joining the posterior interosseous artery.

The image given below shows anterior interosseous artery.

A negative result of the modified Allens test implies that the ulnar circulation is inadequate, hence, the radial artery should not be punctured. In such cases, the modified Allen's test is

performed on the other hand, which is likely to have a normal circulation.

The integrity of the arcuate system of the hand is assessed by modified Allen's test which is performed routinely before instrumentation of the radial artery.

The test determines the integrity between superficial and deep palmar arches and the patency of the radial and ulnar arteries at the wrist. Each one of the arteries is compressed at a time. The individual artery which is sufficient to maintain the arterial supply to the hand in isolation is noted.

Procedure:

• The patient makes a tight fist, examiner digitally compresses both ulnar and radial arteries.
• The patient opens the fist to reveal the pale palm.
• Ulnar artery compression is removed, palm turns red including the thumb zone (positive modified Allen's test).
• If blood fails to return to the palm including the thumb zone, it reveals the anastomosis between the 2 palmar arches is inadequate (negative modified Allen's test).

If the hand does not flush within 5–15 seconds (modified Allen's test negative), it indicates that ulnar circulation is inadequate or nonexistent. In this situation, the radial artery supplying arterial blood to that hand should not be punctured.

The process of dialysis occurs over many hours and requires considerable flow rates of 250-500 mL/minute.

As no vein in the peripheral limbs has such high flow, a surgical procedure (AV fistulas) is necessary to create such a system.

Two types of arteriovenous fistulas:

• The radial artery is anastomosed to the cephalic vein in the wrist (most common)
• The brachial artery is anastomosed to the cephalic vein at the elbow

The following image shows radiocephalic and brachiocephalic fistula respectively.

The palmar venous network in the palm of the hand gives rise to the median antebrachial vein.

The median antebrachial vein is a superficial vein of the anterior forearm. It drains the superficial structures of the forearm and wrist. It ascends to the cubital fossa where it drains into the medial cephalic and median basilic veins in an inverted Y-shaped configuration.

The dorsal venous network on the dorsum of the hand gives rise to cephalic and basilic veins as shown below.

The antecubital vein (median cubital vein) is usually the vein preferred for direct blood investigations.

The median cubital vein connects the cephalic vein to the basilic vein at the roof of the cubital fossa. It lies superficial to bicipital aponeurosis and hence is easily accessible. It is used for IV

injections, blood transfusions, and blood withdrawal.

Option A: The cephalic vein begins as a radial continuation of the dorsal venous arch, runs on the roof of the anatomical snuffbox. It ends in the axillary vein. It is connected to the basilic vein

by the median cubital vein. It is the preferred site for short-term IV cannula.

Option C: The basilic vein drains the ulnar end of the dorsal venous arch, passing on the medial aspect of the forearm. It pierces deep fascia at the elbow and joins venae comitantes of brachial artery forming the axillary vein, at the lower border of teres major.

Option D: The brachial vein is a deep vein of the forearm which lies on either side of the brachial artery. It is formed by joining the venae comitantes of radial and ulnar arteries. It joins the axillary vein at the lower border of the teres major.